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descompune in factori expresia: 81-a^{2}-2*a*b-b^{2}.[tex] x^{2} [/tex]

Răspuns :

81-a²-2ab-b²=9²-(a²+2ab+b²)=9²-(a+b)²=(9-a-b)(9+a+b)
81-a²-2ab-b²=9²-(a²+2ab+b²)=9²-(a+b)²=(9-a-b)(9+a+b)